1. Field of the Invention
The invention relates to methods for manufacturing silicon rich oxide (SRO), and more particularly, to methods for manufacturing semiconductor devices incorporating one or more regions of SRO.
2. Description of the Related Art
Charge storage devices incorporating SRO have been receiving increasing attention as a result of various advantages provided by the SRO when utilized as a charge trapping layer. Controlling the ratio of Si and SiO2 in the SRO material incorporated in dynamic random access memory (DRAM) devices can provide improved electrical characteristics relative to conventional DRAM devices. In particular, annealing a SRO having an appropriate atomic ratio of silicon and oxygen atoms (Si:O ratio) at a sufficiently high temperature will tend to cause segregation of Si and SiO2 within the SRO layer. Accordingly, annealing such SRO materials in this manner can form Si dots that are distinct from the SiO2. A memory device incorporating Si nanocrystals generated using such a Si dot formation technique is discussed in, for example, U.S. Pat. No. 6,690,059, the contents of which are incorporated herein, in its entirety and to the extent consistent with the present disclosure, by reference.
In general, SRO materials can be formed by chemical vapor deposition (CVD) or atomic layer deposition (ALD) processes. CVD processes, however, while generally providing better control over the Si:O ratio than ALD processes, tend to exhibit poor step coverage due to plasma shielding effect. Conversely, ALD processes, while generally providing better step coverage than CVD processes, tend to exhibit poor control over the Si:O ratio within the SRO layer due to the nature of the exchange reaction between a precursor, for example, tetraethoxysilane (TEOS, (Si(OC2H5)4, also referred to in the alternative as tetraethosiloxane or tetraethylorthosilicate), and an oxidation agent, for example, H2O.